Identities, people's subjectively construed understandings of who they were, are and desire to become, are implicated in, and thus key to understanding and explaining, almost everything that happens in and around organizations. The research contribution that this review paper makes is threefold. First, it analyses the often employed but rarely systematically explored concept ‘identity work’, and argues that it is one metaphor among many that may be useful in the analysis of professional and more generally work identities. Second, it focuses on five fundamental, interconnected debates in contemporary identities research centred on notions of choice, stability, coherence, positivity and authenticity. Third, it outlines the roles that the concept ‘identity work’ may play in bridging levels of analysis and disciplinary boundaries, and sketches some possible future identities‐focused ideas for further research. Under‐specification has meant that ‘identity’ has not always fulfilled its analytical promise in either theoretical explorations of identities issues or in empirical studies of identities in practice; and it is to these ends that this paper seeks to contribute.